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Medical Forum / General / Vision / December 2004Re: Input-output and black boxes
<otisbrown@pa.net> wrote: >I believe that a population of natural >eye must be "dynamic". I am only >am interested in this property >of the natural eye which I consider to >be "base-line" and essential >of normal operation. A 50-year-old with +2.00 refractive state requires glasses for "normal operation." That's what Otis calls "natural". >This is the "input" versus "output" >form of testing, where you are >only interested in fundamental >science. Nah.. if you were interested in fundamentals, you'd want to know the relationship of the refractive structures - you know, diopters and curvatures and such, anatomy, physiology, biochemistry, those little details you haven't bothered to study. Your black-box understanding would be OK, limited to "input-output" relationships, if you saw that a) the relationship changes with age, b) normal corrective lenses zero the input, and c) -2.50 anatomical myopes who remove their glasses don't get better. >This is similar to the "perspective" >put on the "facts" by Copernicus >when he put the Sun at the >center of the universe -- in his >day. So according to Otis, Kepler's laws become false if we stand in the wrong place. >I would suggest to anyone who >is developing an education on this >subject (i.e., college students) >consider objective scientific >facts from these two perspectives. Such as the fact that anatomical myopia is not resolved by plus lenses? >They might come to a different >conclusion about the refractive >states of the eye -- other >than the box-camera >"paradigm" that you have >been taught -- and believe >is right. How many box-cameras grow myopic? No answer from Otis. How many box-cameras have muscarinic receptors that affect their dimensions? No answer from Otis. How many box-cameras stop growing myopic if you sprinkle them with pirenzipine? No answer from Otis. -MT Dear Mike, Thanks for your commentary. Perhaps I should clarify. My remarks concern the YOUNG healthy eye that can have refractive states (measured by the individual) from +2.0 to -1.0 diopters -- just to put numbers on it. The data to be reviewed are the refractive states of adolescent primates where both the "output" (refractive status) is measured, and the input "delta" is a change of -0.8 diopters (approximately). The measurements will be made at two week intervals. You are looking to determine if these natural eyes are dynamic (i.e., change their refractive state by direct measurement) or they do not, passive.) Get it? Best, Otis > Perhaps I should clarify. > My remarks concern the YOUNG [quoted text clipped - 3 lines] > +2.0 to -1.0 diopters -- just > to put numbers on it. What is "YOUNG"? The standard deviation of human refractive error declines steadily until the age of 10 or so, when it begins to increase again. This leads me to believe that humans under 10 are significantly more likely to respond to "input" changes. Weisel said that some macaque species don't respond at all to plus or minus lenses, at any age, and the others stopped responding at some age. So which species do you propose to test, and do you intend to generalize the results from a species of monkey to all homo sapiens? > The data to be reviewed > are the refractive states [quoted text clipped - 4 lines] > a change of -0.8 diopters > (approximately). It isn't clear whether you intend to manipulate the environment by enclosing primates in a closed visual environment of 1.2 meters diameter or whether you will force them to wear minus lenses that are 0.8 diopters more minus than their natural state. > The measurements will > be made at two week > intervals. If you like, but "before and after" are all you really need. Instead, how about comparing your treatment group to a similar cohort that you don't treat. Now there's an idea! > You are looking to > determine if these [quoted text clipped - 3 lines] > direct measurement) > or they do not, passive.) I'm not looking to determine this. It sounds a lot like Young's monkey experiments, and he did a pretty good job already. I even stipulate that young humans develop more myopia proportional to the time they spend doing near work, and inversely proportional to working distance. But these relative risks only account for a small percentage of the total myopia. What do we do about the majority, who don't get nearsighted when they put their noses in the book? What do we do with the studies that show family history to be 5 or 10 times more significant, in terms of relative risk? > Get it? Do you get this - http://www.facsnet.org/tools/ref_tutor/epidem/method.php3 http://www.facsnet.org/tools/ref_tutor/epidem/advance.php3 -MT |
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